Help . . . this could be expensive!

[rootmatt]

Before I get depressed, is there likely to be a cheap solution?

I had taken my stock 1982 SC (MUUAAHHAAHHHAAAHHH etc) for a short drive and was giving it a quick squirt before putting it away. It felt as strong as it ever has till I let it hit redline in first gear. I think I heard a noise just as I changed up. Anyhow, it began to run rough. Real rough. Now that it is home, it idles at 700 rpm and sounds like three cylinders are out. Ignition appears fine. The air box is still there and the airflow sensor thingy moves as normal. Haven't checked the bottom of the airbox yet nor dug any deeper.

Any ideas?

Oh, apparently I need to submit a photo. Cop this:

[equality72521]

First, what kind of noise did you hear? What did it sound like?

[SCWDP911]

I am certainly no expert but with what you describe, I wonder if you damaged your distributor in some way...

Good luck. At least you can still be a member of the SCWDP, right?!

[livi]

Sorry, that is a tough one with so little to go on. If it was a 3.2 Carrera I would have known instantly.....yeah sure..

Anyway, what is that greenish looking color! It is spectacular!

Sorry again. If I had read your post thoroughly I would have seen it is Moss Green.

[osidak]

how far into the red did you go -

[911Mac]

I'd tend to think it may be valve train related, it's not clear if you just touched red line or maybe exceeded it. I'd pull the valve covers off and make sure everything looked "normal", no broken rocker arms, valve springs OK etc. You can also check to make sure a head stud didn't break.

Hope it turns out to be something minor.

Mac

[livi]

Wouldn´t the rev limiter save you from any damage on account of high revving ? I believe the stock limiter setting has a reasonable safety margin. No? It was not a sound from missing a gear then ?

[ianc]

Pull plugs, inspect, and then do compression test.

ianc

[rootmatt]

Thanks for the ideas so far. As to your questions:

The revs are limited by a rev-limiting rotor button in the distributor, which was replaced recently and is working;
I believe I stopped short of 7000 rpm before changing up (tachos are never 100% accurate);
The noise I heard was short, like a bang. Sorry, wasn't expecting a noise so I wasn't listening;
So far, I have only inspected the distributor and top of the air box. Both seem to be OK.

I've not removed the valve covers before so I plan to attempt that tomorrow. Valve train or timing chains sounds like a good starting point to explore. How handy I just bought silicon valve cover gaskets from our host. I was planning to adjust the valves but the job seems to have evolved since then.

Don't know whether it makes any difference but the car is a ROW model (will add that to my signature block, shortly). Hence the rev-limiting rotor button.

Oh, and Markus, thanks for the comment on the colour. I like it. It's one of the less common colours.

[Early_S_Man]

Matt,

That is, indeed, a very nice shade ... 265 Oak Green, I believe!

Broken valve spring, would/could have allowed contact between valve and piston near redline, but below ignition cutout point. Compression and leakdown test are a good plan.

Good Luck!

[osidak]

my row had a rev limiting rotor that failed and the end result was

broken rocker, 6 bent valves, cracked head and cylinder

Popped out of gear when I was hard on it and really zinged the engine. Did a full rebuild afterwards.

good luck

[rootmatt]

Hi guys, I'm back!

Well, it aint gonna be cheap. I took off the right rear rocker cover this morning and found some stuff in there (photo). Looks like a valve keeper half. Lower valves seem to be happy so it must come from above. Anyhow, this means an intake valve is without a keeper and that can't be good.

Won't bother to look further just now. Looks like the engine is coming out when I get time to do it. I see a top end rebuild in my future if I'm real lucky. Still, any time spent with a spanner in one's hand is time well spent if it's on a Porsche.

[cstreit]

Bummer, definitely keeper in there, part of a valve seal too I think. If you seem to have a ton of valve clearance all of a sudden, could be bent valves. Do a leakdown test. if all is well perhaps you'll be luck and just had a keeper let go.

[Walko]

Hey nice car bad luck about the motor. Did you buy that one from Gulsons.? It looks like my old SC which had berber interior. ( I traded it to Gulsons in MAY 05 but I know they didn't sell it for ages) Great car and Moss Green always looks great

Michael

[rootmatt]

Hi michael

Yes, it did come from Gulsons. Picked it up March this year. Been pretty good till now. Just the usual minor irritations that were easily fixed.

Good to see you're sticking with the marque.

Matt

PS There are two wires hanging down above the back of the premuffler. They had me guessing for a while. Was there once a euro fog light there? Curiosity is a terrible thing!

[Walko]

Matt,

not sure what the wires are for. Never had a euro fog light at the rear when I owned it.

Michael

[rootmatt]

Thanks Michael

Looks like I'll just have to hook something up to them and see what happens, then. What could go wrong?

Zzzzzt!

Matt

[rootmatt]

Well, it has been a while but I'm back on the road again. If you're still curious, here's what happened.

If I had removed the top valve cover, I'd have found the root of the problem. See the first photo. Number 4 inlet valve had a bad day. As best I can tell, the outer spring broke some time earlier as the flange on the spring seat was ground off. This broken spring would have lead to the valve hitting the piston at peak revs with the inevitable carnage. Strangely, the piston was fine and the valve was slightly bent but the spring retainer and rocker were both snapped in half. No further damage found so it would have been a cheap fix if I hadn't done a few upgrades and "while you're in there" stuff.

Thanks for your help. Now you can check out the photos and feel glad it wasn't you.

Cheers

[ChkbookMechanic]

Ouch, good thing you were able to fix it and get it back on the road again.

[NathanR]

What else did you do "while you were in there"?